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shreshtha writes with this intriguing bit from The Daily Mail: "A tiny satellite thruster which can journey to the Moon on just a tenth of a litre of fuel could usher in a new low-cost space age, its creators hope. The mini-motor weights just a few hundred grams and runs on an ionic chemical compound, using electricity to expel ions and generate thrust. The tiny motor isn't built to blast satellites into orbit — instead, it's to help spacecraft manouevre once they're in space, which previously required bulky, expensive engines."

Seriously, I can travel to the Moon with no fuel if I start in the right position with the right momentum. TFA doesn't tell us much unless the secrets are hidden in the video I'm blocking on the bottom of the page.

The new thruster has nothing to do with getting to the moon or even getting into space. It's a way for a small satellite to maneuver once it is in orbit. It could possibly be used for getting into lunar orbit from low earth orbit, but its intended purpose right now is to help clean up debris.

The propulsion system emits ions at high speed (40 km/s) and is thus very efficient at converting propellant mass to satellite momentum. Thrust is low, but given time, ver lge orbit chanegs are possible. for example, in order to reach lunar orbit from low-Earth orbit, a 3-kg nanosatellite with our motor would travel for about 2 years and consume about 500 grams of fuel"
- Herb Shea

This ion thruster is unique by its extremely small size. we have miniaturized not only the ion emitter, but the entire thruster including high-voltage electronics and tank. Our complete thruster has a mass of 200g (including 100 ml of fuel), thus allowing it to be used on nanosatellites. It is the first high efficiency electric propulsion system that can be used in cubesats and 5kg satellites, such as those being planned for OLFAR
The principle of operation of colloid thruster a bit different from the ion engines used fro instance on SMART-1, which uses ionize Xenon. in our case, we use a particular conductive liquid, an ionic liquid, from which we can extract both positive and negative ions. using a liquid avoids a pressurized tank, and allows for important simplification of the system (no valves, no heavy tanks, all flow controlled by capillary and electrostatic forces. using the ionic liquid allows the same speed as using a gas, but offers one big advantage: since we emit (from 2 chips in parallel) both positive and negative ions, the spacecraft stays electrically neutral, which is essential for electric propulsion to avoid having the ions fly back to the spacecraft. for more conventional electric propulsion systems, only positive ions can be emitted, so a neutralizer is needed to emit electrons to keep the spacecraft charge neutral. not having a neutralizer allows significant mass and power savings.
I'm biased, 'cause I work on this!
http://lmts.epfl.ch/microthust [lmts.epfl.ch]
- Herb Shea

and that is not the big issue, as getting off the ground is always the big expense, but we all know that. This tech can be useful in reducing weight costs for sub orbital payloads though, and probably resembles the design of a DS4G engine. The problem with efficiency in the past is that motors required high voltages to accelerate the ions that collided with the electric field grids. DS4G used a two stage four line grid with the top grid closely spaced and of higher voltage, with an open spaced lower voltage bottom grid. These differences between these stages allow higher velocity without ion grid collision at overall lower voltages resulting in 4x the fuel efficiency of previous engines.